For checking and/or repairing the bottom of a soda recovery boiler, its bottom has to be emptied of the molten salt existing therein. As far as present soda recovery boilers are concerned, this is done by melting a pile of material accumulated at the bottom until the surface of the melt lies on the same level as the normal melt chutes of the soda recovery boiler. After this, plenty of soda melt still remains at the bottom of the recovery boiler, which melt solidifies when it is cooled and must be removed by dissolving it in water or by crushing mechanically. The solution has to be pumped out and the crush has to be moved away from the bottom of the boiler by some method. The diluted solution and the crush leaves the circulation of chemicals and the chemicals are not recovered. This takes time and is difficult and, additionally, causes corrosion at the bottom of the soda recovery boiler. As to the present soda recovery boiler, there is no other practical alternative to empty the bottom of the boiler at the moment. For that reason, a remarkably long time has to be reserved for emptying at a maintenance stop.